Light emitting diodes (LEDs) and organic light emitting diodes (OLEDs) are rapidly replacing existing light sources due to outstanding energy efficiency and long lifespan thereof. Generally, light emitting diodes form a light emitting diode package in conjunction with components such as reflectors, reflector cups, scramblers, housings and the like, so as to be able to maximize optical efficiency through high reflectance. Such components should be able to withstand high temperatures and to minimize deterioration of whiteness due to reflectance reduction and yellowing.
Polyester resins, such as highly heat-resistant polyester resins and the like, are mainly used for the components. However, existing highly heat-resistant polyester resins have problems of extremely slow crystallization rate and deteriorated impact resistance.
To solve these problems, typically, attempts have been made to improve crystallization rate and impact resistance by adding additives such as inorganic fillers, nucleating agents and the like to the polyester resins. However, when an excess amount of the additives is used, there is a concern of rapid reduction in moldability and mechanical properties of the polyester resins.
Korean Patent Laid-open Publication No. 10-2013-0076733 discloses a polyester resin composition including a white pigment and a polyolefin copolymer. However, such a polyester resin composition can still have problems such as slow crystallization rate, poor moldability and molding stability, insufficient improvement in mechanical properties, and the like.
Therefore, there is a need for a polyester resin composition which exhibits excellent properties in terms of mechanical properties, heat resistance, improved moldability and stability by increasing crystallization rate so as to be used as components for light emitting diodes.